Garage door with anti-jamming rollers



Aug. 22, 1967 A. CURTIS GARAGE DOOR WITH ANTI-JAMMING ROLLERS FiledMarch 29, 1965 5 Sheets-Sheet l ATTOP/Yfif g- 22, 19567 G. A CURTIS3,336,968

GARAGE DOOR WITH ANTIJAMMING ROLLERS Filed March 29, 1965 5 Sheets-Sheet5,:

Aug. 22, 1967 cu s 3,336,968

' GARAGE noon WITH ANTI-JAMMING ROLLERS Filed March 1965 5 Sheets-Sheet5 I i Ar'raiA/x Aug. 22, 1967 ca. A. CURTIS I 3, ,968

GARAGE DOOR WITH ANTI-JAMMING ROLLERS Filed March 29, 1965 5Sheets-Sheet 4 INVENTOR Gar 4. (027/5 ATTOE/VE'Y.

Aug. 22, 1967 I Filed March 29, 1965 G. A. CURTIS I 3,336,968

GARAGE DOOR WITH ANTI'JAMMING ROLLERS 5 Sheets-Sheet 5 94 i will Z 7.INVENTOR Gu A (yer/5 United States Patent 6,336,968 GARAGE DOOR WITHANTLJAMMING ROLLERS Guy A. Curtis, 1042 Greyton Road, Cleveland Heights,Ohio 44112 Filed Mar. 29, 1965, Ser. No. 443,248 9 Claims. (Cl. 160-488)This invention relates to overhead articulated lift doors and openerstherefor, and particularly to a reversible driving mechanism and thecombination thereof with a new articulated lift door suspension by whichpositive and efiicient, but safe, opening and closing of the door areconsistently obtained even under adverse weather conditions.

The reversible driving mechanism or opener of the present invention isan improvement on the reversible driving mechanism disclosed in myUnited States Letters 1 Patent No. 3,012,520, issued Dec. 12 1961. Itemploys an 'overload switch operating clutch which is an improvement onthe general type of overhead clutch switch cutout disclosed in my UnitedStates Letters Patent No. 2,825,776, of Mar. 4, 1958.

Several difficulties encountered in connection with overhead articulatedlift doors for garages, with which the present invention is concerned,are pointed out in my above Patent No. 3,012,520.

The present invention, while retaining the door operations and safetyfeatures therein disclosed, operates in a more positive and improvedmanner than prior structures. More specifically, the door opener has apositive mechanical drive, instead of a friction drive, yet one whichcan be released readily for manual operation in event of electric powerfailures. While maintaining a positive and rapid drive, it relieves andabsorbs shocks heretofore imposed on such doors in overcoming theirstatic inertia during starting and in opposing their dynamic inertia asthey reach a fully open or fully closed position, or as they strikeobstructions during their travel.

Another improvement resides in the manner of suspending the door on itstracks so that the raising and lowering forces can be applied at one endonly without causing binding of the door, and so that jamming of thedoor due to ice and snow and the like on the tracks is greatly reducedor eliminated.

Another advantage resides in the overload clutch and cutout switchcombination by which positive operation of the switch, with consequentsafety, is obtained.

Other objects and advantages will become apparent from the followingdescription, wherein reference is made to the drawings, in which:

FIGURE 1 is a right side elevation of an overhead articulated lift doorin closed position, with its left side track and suspension, and itsreversible driving mechanism or opener, the track and connections of thedoor therewith at the right edge of the door being omitted for clearnessin illustration, and the opener and a fragment of the door when the dooris in the raised position being indicated in dotted lines;

FIG. 2 is an enlarged side elevational view of the door operator shownin FIG. 1;

FIG. 3 is an inboard side elevation of the door operator shown in FIG. 2and viewed as indicated by line 3-3 therein;

FIG. 4 is a diagrammatic reduced front elevation of the door and aportion of the tracks, showing the reactionary forces by which forcesimposed on the door by the opener are resisted;

FIG. 5 is an enlarged fragmentary right side elevation of a portion ofthe door and its left side mounting rollers, the track being omitted forclearness in illustration;

FIG. 6 is a fragmentary rear view, partly in section, of the door androller structure of FIG. 5, as viewed from line 66 in FIG. 1 and 5, aportion of the track being broken away for clearness in illustration;

FIGS. 7A and 7B are, respectively, enlarged fragmentary horizontalsectional views of a portion of the door and its left hand track, and istaken on line 7A-7A and 7B7B, respectively, in FIG. 6;

FIG. 8 is a wiring diagram showing the electrical control system for thedoor opener;

FIG. 9 is a fragmentary outboard side elevation of the door opener andoverload clutch switch cutout, and is taken on line 9-9 in FIGURE 3, andshows the relative position of the parts of the overload clutch switchcutout ile the operator is driving the door into fully closed positionand the clutch is slipping, immediately preparatory to tripping of theswitch;

FIG. 10 is a view similar to FIG. 9 showing the position of the overloadclutch switch cutout parts during normal rotation of the clutch Whilethe door is between open and closed positions;

FIG. 11 is a view similar to FIGS. 9 and 10*, but showing the positionof the overload clutch switch cutout parts when the operator is drivingin the door opening direction, the reverse from FIG. 9, into fully openposition, the clutch is slipping, and the switch is about to be trippedin the opposite direction from FIG. 9; and

FIG. 12 is a vertical fragmentary sectional view of the overload clutchswitch cutout, and is taken on the lines 12-12 in FIG. 10, parts thereofbeing shown in elevation for clearness in illustration.

Referring to the drawings, the invention is shown as applied to anarticulated door 1, having three upright horizontally elongated,articulated panels 1a, 1b, and 1c. The panels are hingedly connectedtogether by the hinges 2. The door 1 is suspended and guided for liftingand lowering by tracks 3, arranged at opposite edges of the door,respectively. Since the two tracks are mirror images of each other, onlyone track and the door connections therewith is described herein indetail.

Referring to FIG. 1, the track 3 for the left side of the door isillustrated. This track 3 in FIG. 1, has an upright portion 3a, a curvedportion 3b which extends from the top of the portion 3a rearwardly intoa garageand which is concave downwardly and rearwardly, and which isconnected at its rear end to a horizontal rear portion 30. The track 3is adapted to lie along one vertical edge of the door opening and issupported in the upright position illustrated in FIG. 1, preferably bybeing secured to the garage or building structure.

Such a door must be suspended so as to be easily lifted and loweredwithout binding on the tracks due to any cantilever effect or to theforces imposed for lifting and lowering the door.

For example, as illustrated in FIG. 4, the door 1 may be from 8 to 15feet Wide. Assuming the door is in lowered position, and the upwardforce indicated by the letter F is applied at the upper left corner forraising the door, a turning moment, indicated by the arrow M is imposed,tending to rock the door edgewise clockwise in FIG. 4. The moment M mustbe withstood by reactionary forces, indicated by arrows UR at the topand arrow LR at the bottom.

On the other hand, if a downward force indicated by the dotted arrow Fis applied to the upper left corner, it produces a turning moment,indicated by the dotted arrow M which is relatively minor because theright end of the door is continuously urged downwardly by the doorWeight.

To assure the application of these forces while eliminating binding ofthe door 1 in the tracks 3, the left hand edge of the door is providedwith rollers 5, 6, 7, and 8. The rollers 5, 6, and 7 are arrangedadjacent the tops of the panels 1a, 1b and 10, respectively. The bottomroller 8 is adjacent the bottom of the lowermost panel 1c.

All rollers are mounted on suitable brackets 9 which are secured to thedoor by suitable bolts 10. In the form illustrated, the rollers 5 and 8are conventional rollers such as usually provided on such doors, and arealike in form and function. These conventional rollers generally aremounted on pivots, or have their pivots mounted, so that the rollers canmigrate slightly axially to accommodate themselves to departures ofportions of the track form in the normal track width or straightness.

The rollers 6 and 7 are duplicate dual rollers and are best illustratedin FIGS. 5 through 8 wherein the roller 7 is referred to in detail. Theroller 7 comprises a rocker 12 on which separate rollers 13,respectively, are mounted with their axes in spaced relation endwise ofthe rocker 12. The rocker 12 is connected by a rock shaft 14 to itsassociated bracket 9, the shaft being held in fixed position axially bya collar 15 so that it can resist thrusts edgewise of the door. The axisof the shaft 14 is horizontal and lies in a plane parallel to itsassociated door panel. The rollers 13 are mounted on pintles 16,respectively, for rotation relative thereto and preferably in fixedposition axially thereof. The pentiles 16 are secured to the rocker 12in fixed axial position relative thereto. The pintles 16, and therefore,the axes of rotation of the rollers 13, lie in horizontal planes,respectively, but each is oblique to the axis of the shaft 14 foreffecting the proper cooperation of its roller 13 with the track. Withdual rollers 13, the rock shaft may or may not rock slightly about itsaxis as the dual rollers 13 and rocker 12 assure that the axes of thepintles 16 will retain their initial obliquity with respect to the axisof the shaft 14.

Referring to FIGS. 5 through 78, each track 3 has a front margin 17 anda rear margin 18, and is arranged so that it has at least two paralleltrack faces 20 and 21 spaced apart from each other edgewise of the door.For example, in the form illustrated in FIGS. 7A and 7B, the face 20 isoutboard, edgewise of the door, and the face 21 is inboard, and both areon the rear margin 18. For purposes later to be described, the faces 20and 21 ar shown as parts of a continuous surface curvilinear and concavetoward the front margin 17. When these faces are at one margin of thetrack, as illustrated, the obliquity of the pintles 16 of the rollers 13is such that one of the rollers 13 engages the outboard track face 20and the other engages the inboard track face 21.

The upper roller 5 and the bottom roller 8 may be mounted on pintles 22,respectively, which are horizontal. The pintles 22 may be secured withtheir axes in a fixed oblique position also, and if so the obliquity ofthe bottom roller 8 is opposite from that of the upper roller 5, so thatthe roller 8 normally engages the outboard track face 20 and the roller5 and the inboard track face 21. Thus it will be seen that since theinboard track face 21 faces generally away from the adjacent edge of thedoor, it provides the reactionary forces such as UR and conversely, theoutboard track face 20 provides the reactionary forces such as LR Theforces UR and LR thereby resist the moment M as the door is being raisedby the force P of the opener. Corresponding rollers may be provided onthe right edge of the door to resist the moment M in like manner, ifdesired. The rollers 6 and '7 cooperate for guided rolling movement ofthe door along the tracks. Due to the curvilinear continuous surface ofthe concave face of the margin 18, snow, ice, and contaminating foreignmatter are easily dislodged. The rollers can selfadjust toirregularities in the faces 20 and 21 by slight movements edgewise ofthe door, and can relieve binding stresses.

The door 1 may be counterbalanced by the conventional spring 23 andcable 23a. One end of the cable is 4 connected to the bottom panel 1a ofthe door and the other end is anchored to the wall of the garage. Oneend of the spring 23 is anchored to the rear wall of the garage. Apulley 24 on the other end of the spring cooperated with the cable forapplying the counterbalancing force of the spring to the door, asillustrated in FIG. 1.

In order to lift and lower the door thus suspended, a door opener 25 isprovided. The door opener 25 comprises a body having a upright wall 25a,top wall 25b, and a bottom wall 250. The top wall is provided with anupwardly extending flange 26 which supports single rollers 27, which canride slightly on the track portion 3b and along the entire length of thetrack portion 30 during operation of the door.

The rollers 27 are mounted on fixed pintle 28, respectively. The axes ofthe pintles 28 preferably lie in parallel vertical planes, and areoblique to the horizontal so that the rollers engage the inboard trackface 21.

Mounted on the bottom wall 25c is an electric motor 31 which drives areduction gear transmission 32, the output shaft 33 of which carries asprocket 34. The sprocket 34, through a chain 35, drives a complementarylarger sprocket 36 which is mounted on, and for co-rotation with, ashaft 37. Mounted on the shaft 37 is a carriage driving sprocket 38,sprocket 36, shaft 37 and driving sprocket 38 being connected forco-rotation in fixed relation to each other.

The sprocket 33 is in driving engagement with a chain 41 The chain 40 issecured alongside the track portions 3b and 3c by suitable anchor means.The anchor means comprise a bracket 41 secured to the rear end of thetrack portion. The bracket 41 has an aperture through which extends arod 42. The forward end of the rod 42 is connected to the chain 40. Ashock absorbing compression spring 43 is mounted on the rod 42 and atone end bears against the bracket 41 and at the other end against anadjustable nut 44.

The anchor means also includes at the forward end of the chain a bracket45 having a flange portion 45a with an aperture therethrough, throughwhich extends a rod 46. The rear end of the rod 46 is connected to thechain 41). The opposite end carries a nut 47 between which and theflange 45a is a shock absorbing spring 48. Thus the chain can be drawnto the tension required, assuring proper operation of the door and atthe same time relieving the chain, door, and operator from undue shockswhen the door opener 25 starts suddenly, or when the door strikes anobstruction or reaches the end of its travel either in rising orlowering.

The bracket 45 may be mounted on the usual backing strip of the track oron a suitable plate on the garage wall structure. It is preferablysupported on a pivot 49 so that it can swing downwardly and permit theopener to move partway along the curved portion 37 of the trackway. Thebrackets 41 and 45 are preferably at an elevation so that the forceapplied by their springs to the chain urge it upwardly out of drivingengagement with the sprocket 38.

To hold the chain 40 in positive driving engagement with the sprocket 38against the force of the springs of the anchor means, a hold-down shoe51 is provided. A rock lever 52 is connected by a pivot 53 to thecarriage 25. The shoe 51 is connected to the lever 52 by a pivot 54 forrocking to self-adjusted position with respect to the chain 40. Theopposite end of the lever 52 is pivotally connected to a depending latcharm 55 having notches 5o for engaging a suitable pin 57 on the carriageat different selected positions of the arm 55. A spring 58 normallyurges the arm 55 is a direction for latching engagement with the pin 57.A chain or cord 59 is connected to the lower end of the arm 55 and hangssufficiently below the carriage 25 so that it can readily be grasped byan operator standing on the floor of the garage and manipulated forreleasing the shoe 51 from the chain in the event it is desired to movethe door manually, as in case of a power failure. It is again noted.creased tension on the spring and .spring 43 or 48, as the case may.operator in either direction, the inertial forces imposed that thechain 40 is supported at its ends normally slightly above the level forproper engagement with the sprocket 38 so that if the shoe 51 is removedfrom the chain 40, then, due to force of the springs 44 and 48, thechain 40 is lifted slightly clear of the sprocket, so that it engages solightly and near the outer ends of the sprocket teeth that the sprocketcan readily slide past the chain by camming the chain 40 upwardly.

The carriage 25 is connected by a link 60 to a suitable bracket 61 onthe door so that as the carriage moves from front to rear along thetrack portions 3b and 30, it can raise the door, and as the carriagemoves from rear to front it can lower the door. By this arrangement avery positive and effective drive is provided. As hereinbeforedescribed, the rollers 27 on the carriage 25 are capable of transferringa reactionary force, such as UR from the track in the outboarddirection. The link 60 and its connection'with the door and carriage aremade sufliciently strong to transmit the force UR to the upper left-handcorner of the door. Thus the rollers 27 are operatively connected to thetop of the door, and can be considered as upper door rollers for thepurpose of preventing cocking of the door on its tracks.

It is desirable that when the door approaches closely or reaches the endof its path of travel, or is stopped by some obstruction while it isbeing lowered or raised, that the electric power to the operator be shutoff. Furthermore, it is desirable that adjustment be provided forstopping the door in the proper either raised or lowered positions. Forthis purpose, adjustable abutment elements 62 may be provided. Theseelements preferably are C- shaped and adapted to receive the chain 40transversely through their open side and to be secured in fixed positionthereon. For this purpose each element 62 is provided with sets ofaligned apertures 63 and 64, through .which pins can be dropped to passbetween the adjacent .pivot pins of the links of the chain, asillustrated in FIG- URE 2. The stop is fastened on the chain 40 in thismanner in a position to be engaged by the adjacent edge of the carriage25, as the carriage moves toward the end of the chain with which theparticular element 62 is associated. When so engaged, the element stopsthe movement of the carriage abruptly relative to the chain, but thesprings 44 and 48 absorb the shock.

It is noted that the set of apertures 63 and 64 are spaced apart adistance so that their pins 66 can pass through adjacent links of thechain. However, the apertures 63 are nearer one end of the element thanthe other set, and certain adjustment is provided in the stop position,depending upon which end of the element 62 is disposed toward thecarriage 25. The spacing of thesets of apertures from the ends ispreferably such that the apertures 63 are spaced from one end one-halfthe distance between the two sets of apertures, and the apertures 64 arespaced from the other end a distance equal to that between the sets ofapertures. The adjustment can be effected readily, by moving the stopposition one link in each direction, or by reversing its ends for movingthe stop position a half link in either direction. It is apparent thatwhen the carriage strikes the forward abutment element 62, and isstopped thereby, it imposes an ina shock thereon, which is relieved bythe spring 43. When it strikes the rear abutment it imposes additionaltension on the spring 48, which relieves the shock and then brings thedoor easily to the desired final position upon the restoration of thebe. Upon starting the are also relieved by one or the other of thesprings 43 and 48.

It is desirable, however, that power to the motor be -cut off promptlyupon the carriage 25 striking either abutment, or upon the door beingstopped by an obstruc- .tion. For this purpose, thecircuit illustratedin FIG. 8

is used for controlling the motor, and the switch of the circuit, inturn, is controlled by an overload clutch switch cutout, later to bedescribed.

As illustrated in FIG. 8, the motor 31 is a reversible motor having afield 70 and an armature 71. The power source includes an extensible andcontractible coiled electric cable comprising the lines L and L whichare connected to external power lines. One terminal of the field isconnected to the line L, and the other terminal to a lead line 73 whichis connected to two terminals 74 and 75 of the reversing switch. Theother line L is connected by a manual or relay operated double throwswitch S to lines 76 and 77 having terminal contacts 78 and 79,respectively. The terminals of the armature are connected to theterminals 80 and 81, respectively, of the blades 82 and 83,respectively, of a double blade, double throw switch, indicatedgenerally at 84.

It will be seen from FIGURE 8 that, assuming the switches S and 84 arein the positions indicated in solid lines, one terminal 71a of thearmature 71 will be connected to the power source through the switch S,line 76, contact 78, and blade 82. The other terminal 71b of thearmature 71 will be connected through blade 83 and line 73, into thesource in series with the field 70. On the other hand, when the switch84 is tripped by the cutout to the position shown in the dotted lines,the armature will be disconnected from the source until the switch S istripped in the opposite direction to the dotted position. When theswitch S is so tripped, the terminal 71b of the armature is connected ina reverse relation, through the switch S, line 77, and blade 83 and theterminal 71a is connected to contact 74 and line 73 to the field 70,thus reversing the armature and field and so reversing the motor.

In order to operate the switch 84, an overload clutch switch cutout suchas described in my US. Letters Patent No. 2,825,776, is provided, thestructure of that patent being modified to provide more positive action.

As mentioned, a sprocket 34 is mounted on, and for rotation with, theoutput shaft 33 of the speed reducer 32. This sprocket, in turn, drivesthe sprocket 38, which moves the carriage along the track. However, whenthe carriage reaches the end of its run, it necessarily prevents furtherrotation of the sprocket 38 and hence of the sprocket 36, which normallywould stop the sprocket 34 and motor. An overload clutch connection isprovided between the sprocket 34 and the shaft 33 normally for causingco-rotation of the sprocket and shaft, but relieving the sprocket 34 andshaft 33 from driving relation by stopping the carriage when thesprocket 34 is stopped.

The overload clutch switch cutout comprises a plate 85 having a hub 86secured by a key 87' to the shaft 33 for co-rotation therewith. Mountedon the shaft for rotation relative thereto is a cup 88 which isconnected by a suitable spline 89 to the hub of the sprocket 34 forco-rotation therewith. The cup 88 has a bottom wall 88a and a peripheralside wall 881). The outer end of the shaft 33 carries a wing nut 94)between which and the hub 86 of the plate 85 a compression spring 91 isdisposed. The compression of the spring may be adjusted and the springurges the plate 85 endwise of the shaft 33 toward the bottom of the cup88. On the bottom wall 88a of the cup 88 is a friction brake lining 92which engages the adjacent face of the plate 85 and provides a frictiondrive through the shaft 33 and plate 85 to the cup 88. This frictiondrive is adequate to drive the carriage 25 along the track through thesprocket 36 and chain 40. However, when the carriage 25 strikes one ofthe abutment elements 62, it is stopped and thereby stops the sprockets38, 36, and 34 and the cup 88. This overloads the clutch so that theplate 85 is rotated relative to the cup 88 by the motor 31.

In order to trip the switch 84 at such time, a switch tripping device ismounted on the plate 85. In the form illustrated, this device comprisesa shaft 93 rigid with the plate 85 and parallel to, and eccentric to,the axis of the shaft 33. A friction roller 94 is mounted on the shaft93 for rotation relative thereto. A switch tripping device, including adisc 95, having a hub 95a, is also mounted on the shaft 93 for rotationrelative thereto. A friction spring washer 96 is interposed between theend of the roller 94 and the disc 95 for providing a light frictionaldrive so that the two co-rotate together when free to rotate. It isapparent that upon stoppage of the cup 88 and continued rotation of theplate 85, the roller 94 rolls along the inside of the side Wall 8812 ofthe cup 88. The disc 95 has an inturned finger 97 which engages the sideWall 8812 of the cup and limits the rotation of the disc 85 in eitherdirection of rotation about the axis of the shaft 93 after rotation ofthe disc through about 270 from either of its extreme positions.

Thus, referring to FIGURE 9, let it be assumed that the motor is drivingthe carriage in a forward direction, the clutch is slipping, and theswitch 84 is about to be tripped. Due to rotation of the plate 85'relative to the cup 88 in the direction indicated by the arrow a, roller94 rolls along inside of the side wall 88b of the cup in the directionindicated by the arrow 12. This rotation continues until the finger 97strikes the inner wall 88b and'arrests further rotation of the disc 95.The roller may continue rotating, but the disc 95 will remain fixedly inposition and restrained against further rotation in the directionindicated by the arrow b,,the spring washer 96 slipping so long as thedisc 95 is thus restrained. The spring washer 96 is adequate to provideonly a very light pressure for rotating the disc 95 when the disc isfree and unrestrained otherwise.

Mounted on the disc 95 is a generally W-shaped semifloating trip finger98 which is urged by a spring 99 against pins 100 on the disc 95. InFIGURE 9, one end 98a of the finger 98 is positioned to engage a lever102 of the reversing switch 84 and throw it in a direction indicated bythe arrow c. When the finger 98 engages the lever, the disc isconstrained .by the finger 97 from continuing rotation in the directionindicated by the arrow b. Hence the finger 98 throws the switch lever102 in the direction indicated by the arrow c. The final position in thedirection indicated by the arrow must be such that the lever can bere-engaged upon reversal of the rotation of the plate 85, yet the finger98 must pass the lever in the direction of the arrow c. For this purposethe spring 99 is provided, and permits the finger to snap past the endof the lever 102 and return into the path of the lever for operating thelever upon reversal of the rotation of the plate 85.

Upon reversal of the carriage 25', the plate 85 and cup 88 rotatetogether in a direction indicated in FIGURE by the arrow d. However,when moving in this direction, the same end of the finger 98 againstrikes the end of the lever 102. Since the washer 96 affords littleresistance to free rotation of the disc 95, as the finger 98 strikes theend of the lever 102, the disc 95 is rotated by the lever 102 to theposition illustrated in FIGURE 10. The finger 97 thereby is moved awayfrom the wall 88b, thus rendering the finger 98 inoperative to operatethe lever 102.

Assuming, therefore, that the carriage continues rearwardly until itstrikes the rear element 62, then, as illustrated in FIGURE 11, theplate 85 is caused to rotate, indicated by the arrow e, thus causing theroller 94 to rotate as indicated by the arrow 1. This rotation continuesuntil the finger 97 strikes the interior of the wall 88b of the cup 88and arrests further movement in the same direction. This disposes theother end of the finger 98 in position to strike the lever 102 and moveit in the direction indicated by the arrow g, in FIG. 11. In thisposition it throws the switch to the reverse position from that in whichit was operating.

Upon the next reversal, the finger 98 would again engage the lever 102and thereby be caused to rotate the disc to an ineffective position, asdescribed heretofore, so that the operation can be repeated insuccessive opposite directions.

It is apparent from the foregoing description that the door is wellsuspended so that it cannot jam on the track under the influence oflifting and lowering, but can move freely to raised and loweredposition. Apositive drive is provided for lifting and lowering of thedoor by the operator and this positive drive is not reduced by wear andthe like, as in the case of frictional drives.

Furthermore, complete safety against damage to the operator, track, ordoor is provided by means of the cutout switch. Severe jarring orjamming due to impacts and inertial forces are relieved by the shockabsorbing springs which hold the chain in tensioned condition. Byadjustment of the abutment elements along the chain, positions forthrowing the reversing switch can be selected so that the door coasts toexactly the position without a sudden stop. Furthermore, even though thedrive is positive, it can be released readily in the event of powerfailure so that the door can be raised and lowered by hand. This can beaccomplished by an operator standing on the floor level and merelythrowing the latch lever out.

Having thus described my invention, I claim:

1. An articulated lift door and support comprising a pair of spaced,parallel tracks, each track having a forward upright portion and acoplanar curved portion at the upper end thereof, the coplanar curvedportion being concave rearwardly, an articulated door having articulatedsegments and having its margins adjacent the tracks, respectively, lowerguide rollers mounted on the door near the bottom at its margins,respectively, upper guide rollers operatively connected to the door atthe upper margins, respectively, said upper and lower guide rollers ateach margin of the door being in rolling engagement with the track atthe associated margin, each track having rail inboard and outboard facesextending lengthwise thereof, the out-board face facing generallyinboard toward said one margin of the door and the inboard face facinggenerally outboard away from said one margin of the door, sets of dualupper and lower rocking rollers at the margins of the door arranged oneset adjacent each juncture of adjacent articulated door segments at eachmargin of the door, each set comprising a rocker and an upper roller anda lower roller mounted on the rocker, pivot means connecting each rockerto its associated door segment for rocking about an axis extendinghorizontal and parallel to the plane of the door segment on which therocker is mounted, and means connecting the upper and lower dual rollersof each set to their associated rocker with the axes of the rollerssubstantially horizontal and oblique to the normal plane of theassociated segment of the door, the obliquity being related to the facesso that the lower dual rollers engage and roll along the track facesfacing inboard and the upper rollers roll along the track faces facingoutboard.

2. A structure according to claim 1 wherein each track has an extensionextending rearwardly from the rear end of said curved portion, a singlepower driven carriage is provided and is mounted on one of said tracksfor movement therealong, force transmitting means connects the carriageto the upper portion of the door adjacent said one track for lifting andlowering the door by the carriage as the carriage moves along the track.

3. A structure according to claim 2 wherein the upper guide rollers areon the carriage and the force transmitting means provides the operativeconnection of the upper guide rollers on the carriage with the door.

4. A structure according to claim 1 wherein said faces of each track aredivergent from each other in a direction forwardly and rearwardly of theassociated track.

5. A structure according to claim 1 wherein said faces of each track areareas of a continuous curvilinear surface at one margin of the track andwhich surface is concave toward the opposite margin.

6. A structure according to claim 1 wherein the rockers are constrainedfrom movement relative to the door axially of their pivot means.

7. A structure according to claim 6 wherein the dual rollers of eachrocker are constrained from axial movement relative to their associatedrocker.

8. A structure according to claim 1 wherein the upper guide rollers andlower guide rollers are movable axially relative to the door.

9. A structure according to claim 1 wherein each track has front andrear margins, said track faces of each track are at the same margin ofthe track, the axes of the lower guide rollers are oblique relative to aplane parallel to the normal plane of the door, the axes of the upperguide rollers are oblique to said plane in the 10 opposite directionfrom the axes of the lower guide rollers.

References Cited UNITED STATES PATENTS 1,817,909 8/1931 Blodgett 1601891,848,311 3/1932 Brower 49-199 2,825,776 3/1958 Curtis 20061.462,846,534 8/1958 Morrill 200-61.46 X 2,925,267 2/1960 Volf 160-1883,012,520 12/1961 Curtis 49-199 X 3,066,729 12/1962 Gessell 160-193DAVID J. WILLIAMOWSKY, Primary Examiner. HARRISON R. MOSELEY, Examiner.P. M. CAUN, Assistant Examiner.

1. AN ARTICULATED LIFT DOOR AND SUPPORT COMPRISING A PAIR OF SPACED,PARALLEL TRACKS, EACH TRACK HAVING A FORWARD UPRIGHT PORTION AND ACOPLANAR CURVED PORTION AT THE UPPER END THEREOF, THE COPLANAR CURVEDPORTION BEING CONCAVE REARWARDLY, AN ARTICULATED DOOR HAVING ARTICULATEDSEGMENTS AND HAVING ITS MARGINS ADJACENT THE TRACKS, RESPECTIVELY, LOWERGUIDE ROLLERS MOUNTED ON THE DOOR NEAR THE BOTTOM AT ITS MARGINS,RESPECTIVELY, UPPER GUIDE ROLLERS OPERATIVELY CONNECTED TO THE DOOR ATTHE UPPER MARGINS, RESPECTIVELY, SAID UPPER AND LOWER GUIDE ROLLERS ATEACH MARGIN OF THE DOOR BEING IN ROLLING ENGAGEMENT WITH THE TRACKS ATTHE ASSOCIATED MARGIN, EACH TRACK HAVING RAIL INBOARD AND OUTBOARD FACESEXTENDING LENGTHWISE THEREOF, THE OUTBOARD FACE FACING GENERALLY INBOARDTOWARD SAID ONE MARGING OF THE DOOR AND THE INBOARD FACE FACINGGENERALLY OUTBOARD AWAY FROM SAID ONE MARGIN OF THE DOOR, SETS OF DUALUPPER AND LOWER ROCKING ROLLERS AT THE MARGINGS OF THE DOOR ARRANGED ONESET ADJACENT EACH JUNCTURE OF ADJACENT ARTICULATED DOOR SEGMENTS AT EACHMARGING OF THE DOOR, EACH SET COMPRISING A ROCKER AND AN UPPER ROLLERAND A LOWER ROLLER MOUNTED ON THE ROCKER, PIVOT MEANS CONNECTING EACHROCKER TO ITS ASSOCIATED DOOR SEGMENT FOR ROCKING ABOUT AN AXISEXTENDING HORIZONTAL AND PARALLEL TO THE PLANE OF THE DOOR SEGMENT ONWHICH THE ROCKER IS MOUNTED, AND MEANS CONNECTING THE UPPER AND LOWERDUAL ROLLERS OF EACH SET TO THEIR ASSOCIATED ROCKER WITH THE AXES OF THEROLLERS SUBSTANTIALLY HORIZONTAL AND OBLIQUE TO THE NORMAL PLANE OF THEASSOCIATED SEGMENT OF THE DOOR, THE OBLIQUITY BEING RELATED TO THE FACESSO THAT THE LOWER DUAL ROLLERS ENGAGE AND ROLL ALONG THE TRACK FACESFACING INBOARD AND THE UPPER ROLLERS ROLL ALONG THE TRACK FACES FACINGOUTBOARD.